Ms Collins said she was resigning as a Minister from Cabinet until she could clear her name.

State Services Commissioner Iain Rennie this morning released a statement saying the Commission was contacted by the Prime Minister's Office over the last 24 hours on the issue.

"Any activity that undermines, or has the potential to undermine, the trust and confidence in the public service to impartially serve the interests of the government and New Zealanders is a matter of concern to me.

"It is important that Chief Executives and Ministers mutually support each other to carry out their respective roles, in order to work together to serve the best interests of New Zealand and New Zealanders.

"Ministers are entitled to hold public servants to high standards of trust and performance and, in turn, should respect the role the public service plays," Mr Rennie said.

"I am therefore extremely concerned by an allegation that a Minister has associated with third parties to discuss influencing my assessment of a public service chief executive. If true, this would be wholly unacceptable."

Mr Rennie said he told the Prime Minister's Office that Ms Collins had a positive view of Mr Feeley's performance through her time as Minister responsible for the Serious Fraud Office.

The Commission had reviewed its documentation and sought the recollections of staff responsible for the SFO portfolio at the time, he said.

Mr Rennie said earlier in 2011, Ms Collins had raised with him the appropriateness of Mr Feeley's consumption of a bottle of champagne following a media inquiry.

"It was appropriate that she spoke to me about this matter and my view on the matter was released publicly at the time.